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Nasa’s new planet-hunter to seek Earth-like worlds

Technicians prepare the Transiting Exoplanet Survey Satellite for launch. The spacecraft will prowl for planets around the closest, brightest stars. These newfound worlds eventually will become prime targets for future telescopes looking to tease out any signs of life. AP

Tess is designed as a follow-on to the American space agency’s Kepler spacecraft, which was the first of its kind and launched in 2009. Now, the ageing spacecraft is low on fuel and near the end of its life.

Kepler found a massive trove of exoplanets by focusing on one patch of sky, which contained about 150,000 stars like the Sun.

The Kepler mission found 2,300 confirmed exoplanets and nearly 4,500 candidates. But many were too distant and dim to study further.

Tess, with its four advanced cameras, will scan an area that is 350 times larger, comprising 85 per cent of the sky, in the first two years alone.

“By looking at such a large section of the sky – this kind of stellar real estate – we open up the ability to cherry-pick the best stars to do follow-up science,” said Jenn Burt, a postdoctoral fellow at the Massachusetts Institute of Technology.

“On average, the stars that Tess finds observes be 30 to 100 times brighter and 10 times closer than the stars that Kepler focused on.”

Because Tess uses the same method as Kepler for finding potential planets, by tracking the dimming of light when a celestial body passes in front of a star, the next step is for ground-based and space telescopes to peer closer.

The Hubble Space Telescope, plus the James Webb Space telescope (scheduled to launch in 2020), should be able to reveal more about planets’ mass, density and the make-up of their atmosphere.

“Tess forms a bridge from what we have learnt about exoplanets to date and where we are headed in the future,” said Jeff Volosin, Tess project manager at Nasa’s Goddard Space Flight Centre.

By focusing on planets dozens to hundreds of light years away, Tess should be a stepping stone to future breakthroughs, he said.

“With the hope that someday, in the next decades, we will be able to identify the potential for life to exist outside the solar system.”